1. Field of the Invention
The present invention relates to the employment of gypsum, preferably phosphogypsum, in the suppression of fires.
2. Description of the Prior Art
Large quantities of phosphogypsum are being produced today as a by-product in wet process phosphoric acid plants. In the United States, however, the widespread availability of natural gypsum and its relatively low cost make any large-scale application of phosphogypsum unlikely for the immediate future. Moreover, the cost of transporting phosphogypsum, usually from phosphoric acid plants, remotely located to industrial centers, is generally more expensive than that of nearby natural gypsum. Still further, in many instances, the by-product phosphogypsum requires some purification to remove fluoride and phosphorus before it is suitable for most industrial applications.
A need, therefore, exists today to discover new uses for phosphogypsum (and gypsum), so that total cost of producing phosphoric acid may be lowered and the storage problems associated with the accumulations of the phosphogypsum may be alleviated. Specifically, in the past it has been proposed that phosphogypsum may be employed directly as a setting regulator in cement or plaster or as a soil conditioner. With some purification, it has also been proposed that the by-product phosphogypsum may be converted into gypsum whereby it could be used in industrial or building products such as cement, plaster, wallboard, and the like. However, the demand for unpurified phosphogypsum as a setting regulator or soil conditioner has not kept pace with the increasing supply. Moreover, the purification of phosphogypsum to gypsum usually is too expensive to make the resulting products economically attractive. Therefore, a great need exists for discovering new uses for phosphogypsum which are commercially acceptable.